Bone screws have been used in spinal instrumentation since the 1960s. A pedicle screw is a particular type of bone screw designed for implantation into a vertebral pedicle. The pedicle is a dense stem-like structure that projects from the posterior of a vertebra. There are two pedicles per vertebra that connect to other structures (e.g., lamina, vertebral arch).
During back surgery, particularly in the lumbar area, pedicle screws and rods must be inserted into the vertebrae to provide mechanical support to the spine during the healing and bone fusion process. Typically the pedicle screws are inserted as close as possible to a straight line, to minimize the bends required in the rods that connect them. It is quite difficult to get the connecting rod axis straight, due to the geometry of the spinal bodies, and the inherent curvature of even a healthy spine.
To achieve a fit of a single rod passing through these multiple screws, the surgeon typically will bend a template rod of soft material (e.g., tin), and then attempt to duplicate this rod from much stiffer alloys such as titanium. This duplication process requires much trial and error, and is a difficult, time consuming, and frustrating experience. The longer the rod, the more bends are required, and the more difficult the process.
Based on the foregoing, there is a need for a system and method for automatically forming a pedicle screw rod.